Analysis of the internal contact characteristics of aggregate blend using discrete element method

• Published in: Construction & building materials 2024-08, Vol.438, p.137302, Article 137302
• Main Authors: Yu, Weixiao, Wang, Sudi, Miao, Yinghao
• Format: Article
• Language: English
• Subjects: Aggregate blend; Contact characteristics; Discrete element method; Load transfer
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2024.137302

Aggregates are the main carrier to resist the external loads for asphalt pavement, and the particle contact characteristics in aggregate blend are closely related to the load transfer properties of asphalt mixture. This study analyzed the internal contact characteristics of aggregate blend to provide a reference for revealing load transfer mechanism. Nine types of gradations were selected to perform the discrete element method (DEM) simulation tests of aggregate blends. In the blends, aggregates were divided into main skeleton aggregates and disruption aggregates based on particle function, and the contacts were classified into strong contacts and weak contacts according to the average contact force, and the contact types were divided into the contacts only between main skeleton aggregates (S-S), that between main skeleton aggregates and disruption aggregates (S-D), and that only between disruption aggregates (D-D). On this basis, the indicators for evaluating the contact characteristics between particles were developed. The internal contact characteristics and load transfer properties of aggregate blend were analyzed. The results showed that the proportion of multiple contacts in S-S is higher than that in S-D and D-D, indicating that the interlocking ability of S-S is better than that of S-D and D-D. S-D has the highest number of contacts in stone matrix asphalt (SMA) and open graded friction course (OGFC) gradations, while D-D has the highest number of contacts in dense asphalt concrete (AC) gradations. Most of the contacts in S-S are strong contacts, while that in S-D and D-D are weak contacts. For skeleton asphalt mixtures, most of the external load is transferred in S-S. For AC asphalt mixtures, the external load is mainly transferred in S-D. The average contact force in S-S is much greater than that in S-D and D-D, indicating that S-S has the strongest load transfer ability. The contact length in S-S of AC gradations is longer than that of SMA and OGFC gradations, illustrating that S-S of suspend-dense structures has lower load transfer efficiency compared with skeleton structures. •A series of indicators characterizing the contacts of particles were proposed.•The interlocking ability of S-S is better than that of S-D and D-D.•For skeleton asphalt mixtures, most of the external load is transferred in S-S.•For AC asphalt mixtures, the external load is mainly transferred in S-D.•S-S has better load transfer ability compared with S-D and D-D.